Heat shrinkable member

Abstract

A casing member for forming a connection between tubular sections. The member has heat shrinkable end portions, for connecting on respective adjacent end surfaces of the tubular sections adjacent the joint, and a middle portion for spanning between the end surfaces of the tubular sections. The end portions are formed integrally with at least a portion of the middle portion and have a zone that has a relatively small wall thickness while the middle portion having a relatively large wall thickness. This member may be made by heat shrinking a sleeve on an inner core on a mandrel or by uniting opposed ends of a heat shrink sheet having one or more auxiliary layers bonded to it. The properties of the core or auxiliary layer or layers may be tailored to provide desired properties or capabilities.

What is claimed is:  
     
       1. A casing member for forming a connection between tubular sections having respective end surfaces, the member having heat shrinkable end portions, for connecting on said respective adjacent end surfaces of said tubular sections, and a middle portion for spanning between said end surfaces of said tubular sections, said end portions formed integrally with at least a portion of the middle portion and comprising a zone having a relatively small wall thickness and the middle portion having a relatively large wall thickness, said zones of the end portions being caused to shrink while said middle portion remains unshrunk and remains solid and not melting or flowing when said zones and said middle portion are exposed to similar heat flux for a similar period of time. 
     
     
       2. A member according to  claim 1  wherein the wall thickness of said zone is no more than 95% of the thickness of the middle portion. 
     
     
       3. A member according to  claim 2  wherein the wall thickness of said zone is no more than 70% of the thickness of the middle portion. 
     
     
       4. A member according to  claim 1  wherein each said zone of relatively small thickness extends 5 to 35% the length of the member. 
     
     
       5. A member according to  claim 1  wherein each end portion is of substantially uniform thickness. 
     
     
       6. A member according to  claim 1  wherein each end portion decreases in thickness longitudinally outwardly from the middle portion. 
     
     
       7. A member according to  claim 1  comprising a tubular sleeve having a ratio of the wall thickness of its middle portion to the diameter of the middle portion in the range from 5:1 to 300:1. 
     
     
       8. A member according to  claim 1  having a hole through the middle portion for introduction of a liquid precursor of a foam composition. 
     
     
       9. A member according to  claim 1  wherein each end portion has a degree of shrinkage of 5 to 60% in circumference based on the circumference of the unshrunk end portion. 
     
     
       10. A member according to  claim 9  wherein said middle portion comprises at least a first outer and a second inner layer bonded together, and each end portion is formed integrally with one of said layers. 
     
     
       11. A member according to  claim 1  in the form of a wrap-around sleeve, the wrap-around sleeve comprising a sheet that is at least partially heat shrinkable along a heat shrink direction and that is, or of which sections are, adapted to be formed into the wrap-around sleeve by connecting together edges opposed in the heat shrink direction. 
     
     
       12. A member according to  claim 11  wherein said sheet comprises a heat shrinkable first layer and a second layer laminated thereto and disposed inwardly from the margins of the first layer. 
     
     
       13. A member according to  claim 12  wherein said second layer comprises fiber reinforced plastics material. 
     
     
       14. A member according to  claim 1  comprising a first outer layer including said end portions in the form of a sleeve heat shrunk into conformity with a second inner layer and bonded thereto. 
     
     
       15. A casing member for forming a connection between tubular sections comprising a tubular sleeve having end zones, and wherein at least said end zones are heat shrinkable, said sleeve comprising first and second coaxial plastic sleeve portions bonded together, wherein the second plastic sleeve portion has a degree of crosslinking substantially less than the first plastic sleeve portion, and said tubular sleeve having a hole through said first and second plastic sleeve portions for introducing a liquid precursor of a foam composition to the interior of the tubular sleeve. 
     
     
       16. A member according to  claim 15  wherein said second portion comprises plastics material that is uncrosslinked, or crosslinked to an extent of less than 40%. 
     
     
       17. A member according to  claim 10  wherein said inner and outer layers each comprise transparent or semi-transparent plastics material. 
     
     
       18. A member according to  claim 10  wherein said inner layer comprises fiber reinforced plastics material, sheet metal or a combination thereof. 
     
     
       19. A member according to  claim 10  wherein said layers are bonded by fusion or by an adhesive agent. 
     
     
       20. A member according to  claim 14  wherein said sleeve comprises a sheet heat shrinkable along a heat shrink direction and having edges that are opposed in the shrink direction bonded together at overlap portion, the thickness of which is not more than 80% thicker than the thickness of the remainder of the sheet. 
     
     
       21. A method of forming a composite sleeve member having heat shrinkable end portions comprising disposing an inner covering member on a mandrel, disposing around the inner member and mandrel a sleeve formed from a sheet that is heat shrinkable in the circumferential direction, said sheet having edge portions and said edge portions of the sheet being bonded together at an overlap portion, said sleeve extending beyond either end of the inner member, shrinking the sleeve to conform to the inner member and mandrel, bonding the shrunk sleeve to the inner member to form a composite sleeve member, and removing the composite sleeve member from the mandrel. 
     
     
       22. A method of forming a composite sleeve member for forming a connection between tubular sections, having heat shrinkable end portions comprising providing a first layer that is heat shrinkable in a heat shrink direction, laminating a second layer to the first layer to form a laminate wherein the second layer has sides disposed inwardly from the margins of the first layer and wherein said laminate has edge portions that are spaced apart in the heat shrink direction, and bonding said edge portions together at an overlap portion, said second layer remaining solid and not melting or flowing at the temperature at which the end portions commence heat shrinking during the forming of said connection. 
     
     
       23. A method according to  claim 22  wherein said edge portions of said sheet or first layer are reduced in thickness at least in the portions adjacent the end portions of the sleeve whereby the thickness of the overlap portions where bonded is not more than  80 % thicker than the thickness of the remainder of the sheet or first layer. 
     
     
       24. A method according to  claim 23  wherein said reduced thickness edge portions are chamfered.